1. Field of the Invention
This invention relates to gas lift valve systems and particularly to replaceable gas lift valve system.
2. Description of the Prior Art
Gas lift systems have been used in oil wells to help increase production. In practice, a gas lift mandrel is permanently installed in the production line (either tubing or liners, for example). Once in place, the mandrel can be idle until such time as a gas injection program is desired. At that time, a hole is punched in the side of the gas lift mandrel and a gas lift valve is installed such that gas can be injected into the well between the casing and the production tubing, through the mandrel in to the gas lift valve, which is positioned to transfer the gas from the casing to the production tubing, where it mixes with the oil and aids in the flow of the oil through the production tubing. The main function of the gas lift valve is to meter the flow of gas into the production tubing to maximize the beneficial effects of the gas.
Over time, the gas lift valves corrode and have to be replaced. This operation can be done with current well technology. The major problem with this system is the mandrels are permanently installed. Because the gas and is highly corrosive, eventually, the mandrel fails. When this happens, the control of the flow of gas is eliminated and the gas flows freely into the production tubing, effectively stopping the flow of oil. There is no present way to repair the mandrel and after the mandrel fails, the well is typically shut in and it must be completely reworked to get production restarted. This is a very expensive solution for an aging well.